The present invention relates to an endoscope and a sheath which detachably covers an inserting tube of the endoscope.
Conventionally, the inserting tube of an endoscope is covered with a detachable sheath that is exchanged and discarded after each endoscopic inspection in order to prevent infection between patients via the endoscope.
The sheath includes an elastic tubular portion for covering the inserting tube and a cylindrical supporting portion connected to the proximal end of the tubular portion so as to allow the inserting tube to be inserted into the tubular portion through the supporting portion. The supporting portion is provided with an air feeding conduit for feeding air into and thereby inflating the tubular portion, and a packing for sealing a gap around the inserting tube being passed therethrough to prevent leaking of the air fed into the tubular portion.
The tubular portion is formed to have an inner diameter smaller than the outer diameter of the inserting tube. When inserting the inserting tube into the tubular portion in order to be covered therewith, the tubular portion is inflated by feeding air into it. The air feeding is stopped after the inserting tube has been fully inserted into the sheath so that the tubular portion shrinks and adheres on the inserting tube. In this manner, the inserting tube is covered with the tubular portion of the sheath without having any portion where the tubular portion floats therefrom. The sheath is put on the inserting tube in a manner as above since a floating portion of the sheath may cause the sheath to be snagged and even torn on a body wall when the inserting tube is inserted into a human body.
The conventional sheath, however, is relatively expensive since it is provided with the packing and the conduit for air feeding. Thus, the sheath has been one of the causes of increasing the endoscopic inspection cost.